Tic symptom dimensions and their heritabilities in Tourette's syndrome.

Introduction: Gilles de la Tourette's syndrome (TS) is both genotypically and phenotypically heterogeneous. Gene-finding strategies have had limited success, possibly because of symptom heterogeneity.

Objective: This study aimed at specifically investigating heritabilities of tic symptom factors in a relatively large sample of TS patients and family members.